减去行之间的SQL日期时间

Question

I have a list of table which contains column of program, date, group. I want to find subtraction of date that under same group. for example, my table is:

---

SELECT maxList.program, (maxlist.DATE - minlist.DATE) RUNDATE, maxList 
GROUP FROM ( SELECT a.* FROM schedule a inner join ( SELECT program,Max(DATE) 
FROM schedule GROUP BY program ) b 
ON a.program = b.program )maxList 
inner join ( SELECT a.* FROM schedule a 
inner join ( SELECT program,Min(DATE) FROM schedule 
GROUP BY GROUP ) b 
ON a.program = b.program ) minList 
ON maxList.program = minList. program 


**program  | date                | group**
    a     | 04.12.2013 19:16:08 |   1
    b     | 27.12.2013 00:47:41 |   1
    c     | 30.12.2013 00:47:41 |   1
    d     | 26.12.2013 14:02:42 |   2  
    e     | 31.12.2013 12:03:42 |   2

---

What I want is to subtract the latest date under same group to the initial date. for example 30.12.2013....- 04.12.2013, is there any coding that can be use to apply the subtraction in sql?

Answer 1

Just aggregate the MAX and the MIN :

SELECT   group, 
         MIN(date) || '..' || MAX(date) AS date_range, 
         MAX(date) - MIN(date) AS days_between
FROM     mytable
GROUP BY group

Answer 2

SELECT   group**, MAX(date) - MIN(date) as date_diff
FROM     your_table
GROUP BY group**